<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <script src="/js/vue.js"></script>
</head>
<body>
  <div id="app">
    <div v-if="isShow" ref="self">
        test
    </div>
    <button @click="isShow=!isShow">更新</button>
  </div>
<br>
  <script>
   let app = new Vue({
   el:"#app",
   data:{ 
    isShow:false
      },
    beforeUpdate() {
        console.log('更新之前');
        console.log(this.$refs.self);
    },
    updated() {
        console.log('更新之后');
        console.log(this.$refs.self);
    },
    })
  </script>
</body>
</html>